It seems ironic that just as we eradicated smallpox, a scourge of the early 20th century, a new threat was incubating: HIV. New research shows that those two occurences might actually be related. In the 1950s, the smallpox vaccine was beginning to be withdrawn, as the disease it prevented had been conquered throughout the world. HIV is thought to have begun in the ’50s. But there is more than circumstantial evidence linking the two phenomena.

A recent study demonstrated that immunity to smallpox, triggered by the smallpox vaccine, can actually inhibit replication of the AIDS virus. So foregoing the smallpox immune response may have allowed AIDS to spread freely. While it’s too soon to recommend the long-retired smallpox vaccine to prevent HIV, this research provides the most promising — and ridiculously simple — treatment for early-stage HIV infection to date.